JP-A-10-240008 describes a related art developer cartridge, in which developer is accommodated in a cylindrical resin member. A developer supply opening is provided in a center portion along a cylindrical surface of the resin member. During image formation, developer is supplied to a photosensitive drum from the developer supply opening.
An opening is formed in one side of the resin member. This opening is closed by a cap.
The related developer cartridge can be recycled when an amount of developer remaining in the resin member is equal to or less than a predetermined amount. Specifically, the opening is opened by removing the cap, and air is injected into the resin member from the opening to thereby discharge the residual developer from the developer supply opening together with the air. Then, new developer is filled into the resin member through the opening in the side of the resin member.